The polyamines, spermidine and spermine and the precursor diamine, putrescine have been shown to influence in vitro almost every step in the synthesis of RNA and protein. In seeking to establish their biological role the dilemma presented by these organic cations is which of the many possible actions are manifest in the intact cell. A kinetic approach has been adopted to limit the alternatives and it is proposed to study the biosynthesis of polyamines in the reproductive tract where growth and development can be manipulated to a considerable degree. Emphasis will initially be placed on whether altered ornithine and S-adenosyl methionine decarboxylase activities reflect putrescine, spermidine and spermine formation in vivo. Usine radioactive precursors the extent of incorporation of putrescine into spermidine will be compared with alternate routes of metabolism, such as oxidative deamination via diamine oxidase, tissue binding and release. Bibliographic references: Maudsley, D.V. and Y. Kobayashi. "Hormonal regulation of ornithine decarboxylase in the rat small intestine." Fed. Proc. 34: 702 (1975; Maudsley, D.V. and Y. Kobayashi. "Induction of ornithine decarboxylase in the rat ovary following administration of luteinizing hormone and human chorionic gonadotrophin" Biochem. Pharmacol. 23: 2697-2703 (1974).